GROWTH OF CNXHY FILMS BY REACTIVE MAGNETRON SPUTTERING OF CARBON IN AR NH3 DISCHARGES/

Results on hydrogenated carbon nitride (CNxHy) thin films grown by rea ctive magnetron sputtering in a mixed Ar/NH3 discharge are reported. D epending on the growth temperature (T-s) and negative substrate bias v oltage (V-s), both the composition and the microstructure were altered . Using nuclear reaction analysis and resonant backscattering spectros copy, the maximum N and H content were both 15 at. %. Both the hydroge n and nitrogen content of the films was found to decrease with increas ing growth temperature. The results also show pronounced chemical resp uttering effects, resulting in no net film growth for V-s > 75-100 V. X-ray photoelectron spectroscopy showed no signs of N bound to sp(3) h ybridized C. Also, the microstructure of the films was found to change with T-s. For T-s < 150 degrees C, a structure with crystalline clust ers embedded in an ''fullerene-like'' matrix was observed by high-reso lution transmission electron microscopy. Power-spectra obtained from t he clusters could be identified with the cubic diamond structure. For T-s greater than or equal to 300 degrees C, no crystalline clusters we re found and the films had a homogeneous ''fullerene-like'' microstruc ture with strongly bent planes and closed shell-like features resembli ng bucky-onions. Evaluation of nanoindentation results from the homoge neous ''fullerene-like'' films gave hardness values between 7 and 11 G Pa and elastic recoveries of 55-60%. This should be compared with hard ness and elastic recoveries of 40-60 GPa and 85-90%, respectively, pre viously reported for on nonhydrogenated carbon nitride CNx films grown under the same conditions, but in pure N-2 discharges.